C&T; Muscle and Nervous Tissue Flashcards
what are muscle tissues?
they are elongated cells (muscle cells/muscle fibres/myocytes) that use energy from the hydrolysis of atp to generate force
as a result, muscle tissue produces body movements, maintains poster + generates heat
what are the three types of muscle tissue?
skeletal muscle, cardiac muscle, smooth muscle
what are the features of skeletal muscle?
650
attached to bones via tendons
appear striated, contraction is mostly voluntary except posture
fibres = cylindrical
multinucleate
what are the two important skeletal muscles?
stapedius (smallest)
- stabilizes the smallest human bone in the ear.
- prevents hyperacusis (nerve damage/which produces extra loud sound)
sartorius (longest)
- hip, flexor, lateral rotator
what are the functions of skeletal muscle
motion, posture, eat, protection
what causes striations in muscle fibres?
the striations are caused by highly organised arrangement of myofibrils within the cells.
myofibrils (2um) fill the cytoplasm (sarcoplasm) of the muscle fibre.
what are myofibrils composed of?
filaments (myofilaments)
thin filaments= actin (8nmdiameter, 1-2umlong)
thick filaments = myosin (16nmdiameter, 1-2umlong)
they are arranged in compartments called sarcomeres
what is the connective tissue of skeletal muscle?
epimysium: surrounds anatomical muscle (tendons/bones)
perimysium; around fascicles (collection of muscle cells)
endomysium: around muscle fibres (“cell”), which is the layer for capillaries and nerves.
what are the features of the myofilaments
a band; dark, middle part; contains all the thick filaments
i band; thin filaments, but no thick filaments
h zone; thick filaments, no thin
m line; middle of the sarcomere
z disc; seperate sarcomeres, made up of actinins that link filaments of adjacent sarcomeres.
titin; links z disc to m line, provides resting tension in I band, molecular spring
what are the features of cardiac muscle?
striated; actin + myosin
branched
single central nucleus
involuntary control
fibres join end to end through intercalated discs
what do intercalated discs of cardiac muscle contain?
desmosomes (bind intermediate filaments + provides adhesion in contraction)
gap junctions; communication, coordination + rapid conduction
what are the features of smooth muscle?
short, small spindle shaped
involuntary contarction
non striated (smooth)
single central nucleus
where are smooth muscles located generally?
walls of hollow internal structures
e.g. intestines (peristalsis), blood vessel walls (constriction)
iris of eye, reproductive, digestive, respiratory, urinary, skin erector pili
interesting feature about smooth muscles
they are non striated, but still have bundles of thin/thick filaments
what are dense bodies
functionally similar to z discs
attach to thin filaments, and intermediate filaments
during contraction, tension is transmitted to the intermediate filaments, and the cells twist
